High-throughput screening (HIS) assays for drug discovery and development rely on labels to determine whether a compound binds to the drug target. Label-based assays are time- and labor-intensive, yield limited information, and consume large amounts of expensive biomolecules and chemical libraries. Almost every target requires a different assay; and each new assay can take a year or more to develop. In fact, assay development has become the bottleneck in drug discovery and development, and constitutes a large chunk of the total costs. This SBIR program will develop a label-free, mix-and-measure platform assay, called ?SERS that can be used with any biomolecule target to detect the binding of any small ligand, with little or no assay development. Phase I showed ?SERS is exquisitely sensitive; can detect molecules in the 100-500 Da size range binding to enzymes, lectins, and DMA; can produce information on the binding chemistries involved; and is free from many artifacts that affect other label-free assays. On Phase II, the sensitivity will be improved even further, to enable high-throughput analysis; the assay will be miniaturized, so that only traces of biomolecules and compound libraries are consumed; and demonstrated with a wide range of biomolecules, including DMA, carbohydrates, and diverse proteins. Phase II will also showcase the ability to collect data from complex interactions involving two ligands, monitoring the amount of each ligand that binds, and their impact on each other and on the biomolecule. This platform will have many applications, including cost-effective high-throughput screening for drug lead identification and optimization; rapid in vitro adsorption, distribution, metabolism, and excretion (ADME) and toxicity assays; chemoproteomics (protein interaction profiling with small ligands); and functional glycomics (carbohydrate binding interactions). The platform will be simple to use, very low-cost, and produce a rich body of information on the binding interactions. [unreadable] [unreadable]